The present invention relates to a transmission for a motor vehicle, particularly, to a control apparatus and a control method for controlling an automatic transmission.
Generally, a transmission mechanism included in a gear-type transmission mechanism employs a synchromesh to transmit the rotation of an idle gear mounted on a main shaft (output shaft) smoothly to the main shaft. The synchromesh includes a clutch hub mounted on and engaged with the main shaft by splines. Also, a clutch hub sleeve is provided which is fitted over the clutch hub and provided in its outer surface with a groove in which a shift fork engages. A synchronizer ring is brought into frictional contact with a conical surface of the idle gear by the shifting operation of the shift fork. An operating force exerted thereon by an electrical or fluidic shifting actuator drives the shift fork. The idle gear and the clutch hub sleeve are engaged completely to set the desired gear position. Therefore, the synchromesh is called also a mesh type clutch.
When operating the mesh type clutch by an actuator, such as a fluidic cylinder actuator or an electric motor, a conventional automatic transmission control apparatus controls the actuator so as to push the clutch hub sleeve axially. After the actuator has completely engaged the mesh type clutch, a control signal to remove pressure from the actuator is immediately provided to reduce power consumption and to prevent the contact abrasion of the shift fork and the clutch hub sleeve. The conventional automatic transmission control apparatus detects the travel of the movable member or the sleeve driven for movement by the actuator, decides that the shifting operation is completed upon the increase of the travel beyond a predetermined value and stops the control signal given to the actuator to remove the pressure axially pushing the sleeve.
But, different measuring devices, such as a stroke measuring device, for measuring the travel of the operating member of the actuator have different characteristics, respectively, and hence the accurate detection of the engagement of the mesh type clutch is difficult. Hence, the pressure produced by the actuator can decrease before the mesh type clutch is engaged completely. In such a case, the clutch hub sleeve moves to a neutral position and the actuator performs the pushing operation again.
The present invention provides an automatic transmission control apparatus and an automatic transmission control method capable of surely engaging a clutch to set a desired gear position and allow stable shifting.
In an object of the present invention an apparatus for controlling an automatic transmission of a motor vehicle having an engine and an automatic transmission including a clutch with an actuator for changing gear position is provided. The apparatus further comprises a detecting means for detecting a completion of the gear change and a signal generating means for generating a control signal to the actuator for applying continued pressure to the clutch for a predetermined time after the detecting means detects the completion of the gear change.
In another object of the present invention an apparatus for controlling an automatic transmission of a motor vehicle having an engine and an automatic transmission including a mesh clutch with an actuator for changing gear position is provided. The apparatus further comprises a detecting means for detecting a completion of the gear change and a signal generating means for generating a control signal to the actuator for applying continued pressure to the clutch for a predetermined time after the detecting means detects the completion of the gear change.
In yet another object of the present invention an apparatus for controlling an automatic transmission of a motor vehicle having an engine and an automatic transmission including a clutch with an actuator for changing gear position is provided. The apparatus further comprises a detecting means for detecting a completion of the gear change and a signal generating means for generating a control signal to the actuator for applying continued pressure to the clutch for greater than about 200 ms after the completion of the gear change.
In yet another object of the present invention an apparatus for controlling an automatic transmission of a motor vehicle having an engine and an automatic transmission including a clutch with an actuator for changing gear position is provided. The apparatus further comprises a detecting means for detecting a completion of the changing gear position and a signal generating means for generating a control signal to the actuator for applying continued pressure to the clutch for at least greater than about 200 ms after the completion of the changing gear position.
In another object of the present invention a method for controlling an automatic transmission of a motor vehicle is provided utilizing the above described apparatus. Also, the present invention provides a motor vehicle utilizing the apparatus of the present invention.